Strong Ligand Coordination Enabled Multiphase Ceramic Nanofibers for Simultaneously Enhancing Structural Stability and Infrared Reflection.

Ceramic fibers are promising candidates for lightweight thermal insulation in extreme environments; however, their practical applicability is often constrained by high-temperature phase transitions that trigger rapid grain coarsening and structural degradation. Simultaneously achieving long-term thermal stability and strong infrared reflectivity remains particularly challenging, as these functionalities tend to deteriorate under sustained thermal loading. Here, we develop a strong ligand-coordination strategy in which reactive metal precursors are stabilized by carboxylic acids to form a homogeneous multicomponent sol. Assisted by buffering phase zirconia between the alumina skeleton and infrared-reflective titanium oxide species, the resulting ceramic nanofibers exhibit mechanical robustness, outstanding thermal insulation capability, and infrared reflection under harsh conditions. Notably, the fibers sustain reliable operation at temperatures up to 1300°C even at high titania loading, which is attributed to the collective lattice confinement effect of the alumina matrix and zirconia strengthening phase. Furthermore, thermal conductivity measurements conducted on dense pellets prepared from grounded fibers with the transient laser flash method reveal a continuous decrease in thermal conductivity, giving direct evidence of intensified phonon scattering at elevated temperatures. This work provides an effective strategy for designing flexible ceramic fibers integrating exceptional thermal insulation and multifunctionality for operation in extreme environments.